Global Specialties PB-505 - Manual - Manual (Page 13)

13
CHECKING OUT THE PB-505
The PB-505 may be checked out for proper operation by connecting the AC line cord to
a suitable receptacle. The two 7-segment displays should light when the power switch is
turned on.
Using a DC voltmeter, check for +5 volts between the ground terminal and the +5V
terminal. Repeat the measurement for the positive (+) variable supply terminal and the
negative (-) variable supply terminal. Check the variability of each supply by turning the
appropriate adjusting knob. To test the logic indicators, switch the +5/ +V operating
voltage switch to the +5 position. The TTL/CMOS threshold switch can be in either
position. With no input to the logic indicators, all LEDs should be turned off. Connect
one end of a jumper wire to the +5 volts terminal and the other end to logic indicator 1;
the red LED of logic indicator 1 should light. Repeat this test for logic indicators 2
through 8. Disconnect the jumper from the +5 volt terminal and connect it to the ground
terminal. Connect the other end to logic indicator 1; the green LED of logic indicator 1
should light. Repeat this test for logic indicators 2 through 8.
The function generator may be tested by connecting its output to one of the speaker
inputs. Connect the other speaker input to one of the ground terminal. Switch the
function generator range switch to 1KHz. Turn the frequency control pot clockwise.
Move the amplitude control clockwise until you hear a tone coming from the speaker.
Switch the waveform selector to select sine, square, and triangle. A changing but clearly
audible tone should be heard in each position of the frequency control should vary the
pitch of the tone. The TTL Pulse is available when the function generator is set to
Square Wave.
If an oscilloscope is available, you may check the function generator for proper
waveform and frequency using standard measurement techniques.
The debounced push-buttons can be checked by connecting one side of a resistor (20
ohms, to 100K) to +5 volts and the other side to PB-1, the NC point. Then connect PB-1
to LED-1 with the Logic Indicator +5/ +V switch in the +5V position, the red LED should
light when PB1 is pressed and the green LED should light when PB1 is released. Next,
move the connections from PB1-1 to PB2-1, the NO point. Now the red LED should be
lit when PB1 is not pressed, and the green LED should be lit when PB1 is pressed.
Repeat these steps to test PB2.
The logic switches can be tested by connecting the output of logic switches 1 through 8
to the input of logic indicators 1 through 8. Switch the logic switch +5V/ +V operating
voltage switch to +5, and switch the logic indicator +5/+v operating voltage switch to +5.
Select the CMOS position on the logic indicator TTL/CMOS threshold select switch.
Now the logic indicators should reflect the conditions of the logic switches, that is, red
LEDs will indicate switches in the high (logic "\") position and green LEDs will indicate
switches in the low (logic "0") position. Move each switch between its high and low
position to verify proper functioning. Switch the logic +5/ +V high level switch to +V and